Effect of Locally Available Aggregate Shape on Properties of Fresh and Hardened Concrete

Abstract

The coarse aggregate fraction in concrete occupies at least 50% of its volume; the mineralogy and surface properties of coarse aggregate exert a considerable influence on the properties of concrete. This paper presents the study regarding effect of different shapes of coarse aggregate on properties of fresh and hardened concrete manufactured by mixing indigenous materials. Three shapes of aggregate i.e., flaky, elongated and rounded, were used keeping water cement ratio 0.60 and concrete cast in two mix ratios (1:2:4 and 1:1.5:3). For each mix ratio, 6 batches were cast with varying proportions of these shapes. Nine cubes and eighteen cylinders were cast for each batch. For workability, slump test was performed on each batch in fresh state. For compressive strength, 3 cubes and 3 cylinders from each batch were tested after 3, 7, and 28 days respectively. Similarly, for tensile strength, split cylinder test was performed on 3 cylinders from each batch after 3, 7, and 28 days respectively. ASTM and British standards are followed during testing. Fine and coarse aggregates used were conforming to standard sieve requirements. The results of study show that the shape of aggregate has a significant effect on the performance of concrete. Workability of concrete increases with increasing ratio of rounded aggregates. Similarly, Compressive as well as Tensile strengths of concrete increase with increasing ratio of rounded aggregates. However, compressive strength of concrete with elongated particles is more than with flaky particles while Tensile strength of concrete with flaky particles is more as compared to the concrete using elongated particles.